Space heater

ABSTRACT

A compact portable space heater for heating large areas, the heater having two input centrifugal fans and one rectangular output duct to provide a flow of uniformly heated air in the output duct. The fans are disposed one above the other to provide a narrow profile such that the heater can be wheeled through an average hinged door, the vertical disposition of the fans also contributing to the evenness of the heat distribution across the output duct. A large volume of air is provided for the burner in relation to the heat produced to reduce the unburned products of combustion to a minimum.

United States Patent 1 1 Alms et al.

SPACE HEATER Inventors: Erhard E. Alms, Barrington; James E. Mitchell, Cary, both of I11.

[21] Appl. No.: 205,982

1451 July 31,1973

3,482,825 12/1969 Bjerkan 263/l9 A Primary Examiner-Edward G. Favors Attorney-Charles F. Voytech [57] ABSTRACT A compact portable space heater for heating large areas, the heater having two input centrifugal fans and one rectangular output duct to provide a flow of uniformly heated air in the output duct. The fans are dis- 52 us. on. 432/222, 432/88 Posed one above the other to P d a narrow Profile [51] Int. Cl. F23l 5/02 Such that the heater can be wheeled through an average 58 Field of Search 263/19 A; 431/351 hinged deer, the vertical disposition of the fans also contributing to the evenness of the heat distribution 5 R f n Cited across the output duct. A large volume of air is pro- UNITED STATES PATENTS vided for the burner in relation to the heat produced to 3 210 059 0/1965 N t al 263/19 A reduce the unburned products of combustion to a minies 1 e 2,553,516 5/1931 French 263/19 A R25,626 7/1964 Yeo et al. 263/19 A 3 Claims, 4 Drawing Figures 1 16 a?" 24 22 ---v-- 4 iii w-30* Im/ 185/ I ll :22;

1 I Q g 22 0 77 I! ,2 I 1/ +3 ,9 23

SPACE HEATER This invention relates to portable space heaters capable of producing large quantities of heated air for use in buildings under construction or undergoing remodelmg.

In a co-pending application of Erhard E. Alms for Temporary Heating System for Multi-Level-Buildings, Ser. No. 543 filed Jan. 5, I970 now US. Pat. No. 3,638,858, there is disclosed a space heater mounted on wheels for moving the heater about in a building under construction or undergoing remodeling. The heater is designed to be wheeled through doorways and hence is made as narrow and light as possible. However, the smallest size manufactured is 364% inches wide and has a plenum diameter which is circular in cross section to accommodate a radial blade-type fan. The controls for the burner and fan are mounted to one side of the plenum chamber for accessibility, and the fan can be shrouded with canvas or the like so that its intake end can be made to extend through a doorway or window to the outside of the building. Because of the limited space available in doorways and the circular cross section of the plenum chamber, the cross sectional area of the plenum chamber is relatively limited, and large heating capacity can be obtained only by providing a large movement f air per unit time through the chamber. In the example given, the cross sectional area of the outlet from the heater is approximately 320 sq. inches, and the air delivery is approximately 6,000 c.f.m. so that the velocity of the air past the burner is quite high thus lowering the efficiency of combustion.

It is an object of this invention to provide a portable space heater of large heat capacity which is narrower than those previously available and yet will deliver large quantities of heated air of maximum cleanliness.

As a more specific object, this invention seeks to provide a portable space heater of large heat capacity in which air for combustion is supplied to a substantially rectangular burner with a minimum of swirling motion so that all parts of the burner receive the same amount of air, thus to increase the efficiency of combustion and reduce the quantity of unburned products issuing from the burner.

A further specific object of this invention is to provide a portable space heater in which a greater volume of air is supplied to the burner thereof than in large space heaters heretofore available to complete to a much greater extent the combustion of the fuel and thus to reduce the amount of unburned components in the output of the burner.

These and other objects of this invention will become apparent from the following detailed description of a preferred embodiment thereof when taken together with the accompanying drawings in which FIG. 1 is a side elevational view, partly in section, of the heater;

FIG. 2 is an elevation in perspective of the heater showing the rear and opposite side of the heater;

FIG. 3 is an end elevational view of the heater looking to the left in FIG. 1 as shown by the arrows 3-3; and

FIG. 4 is a diagrammatic representation of the velocity of the air issuing from various locations at the output of the blower.

In the preferred form selected to illustrate this invention, the heater has a single burner of narrow configuration disposed in the combined outlets of two centrifugal blowers, the outlets being rectangular and mounted one above and to the rear of the other. The two blowers are belt-driven from a single motor mounted on a frame below the upper blower in space formed between the two blowers. The two outlets from the blowers are combined by appropriate ducts into a single outlet of approximately the same area and overall outline as the two outlets. The frame is generally rectangular and mounted on a pair of wheels, and suitable handle means are provided for pushing or pulling the heater to a desired location.

Referring now to the drawings for a detailed description of the invention, the heater is comprised of a frame 10 which may be appropriately made from angle iron to mount a pair of wheels 11 slightly forward of the center of gravity of the heater, a stand 12 to support the heater in horizontal position when it is in use or at rest, and a handle 13 located behind frame 10 by which an operator can push or pull the heater from one location to another.

Also mounted on frame 10 are a pair of blowers I4, 15 of the centrifugal type the construction of which is well known and which are shown, therefore, only schematically. The blades of the blowers (not shown) are driven by individual pulleys l6 and 17 each of which is connected by belts l8 and 19, respectively, to a common double pulley 20 driven by a motor 21.

The blades of the blowers l4 and 15 are shrouded in a manner to leave central inlet openings 22, 23 on each side of the blower disposed concentrically with the axes of the pulleys l6 and 17. The outlet opening for each fan is substantially square as shown more clearly in FIG. 3 at 24 and 25, and each outlet is connected to the same single rectangular furnace 26. Said furnace is provided with a rectangular extension 27 passing over blower 15 into which the output of blower I4 is connected.

A single burner 28 of substantially rectangular configuration is disposed inthe furnace 26 and is connected by appropriate means (not shown) through appropriate controls shown generally at 29 in FIG. 2 to a source of LP. or natural gas to be burned in the burner 28. Said furnace 26 extends to the right of burner 28 as shown in FIG. I to provide a plenum chamber 30 in which the substantially complete combustion of the gas takes place together with a mixing of the products of combustion with air from blowers l4 and 15 to produce a stream of air at a desired predetermined temperature. Said stream issues from the rectangular outlet end 31 of the furnace in a substantially straight line without a swirl or helical motion.

Furnace 26 is preferably of double wall construction particularly in the region surrounding burner 28 and immediately downstream thereof to permit air directly from the blowers to pass therethrough and thereby maintain the outer wall of the furnace at a temperature which makes the wall safe to touch without injury.

The inlet openings 22 and 23 on both sides of the blowers as well as pulleys l6 and 17 and the associated drive machanism therefor are covered by openwork guards 32, 33 each of single circular configuration and spanning both blower inlet openings.

To insure as complete combustion of the gas in the plenum chamber 30 as possible, a large ratio of air to fuel burned is maintained in the burner of this invention. In the example illustrated, the air delivered from the outlet end 31 is approximately 4,800 c.f.m., and the maximum B.T.U.s delivered per minute is 1,000,000. ln prior heaters, for the same B.T.U. output, the c.f.m. of air delivered at the output end varied from 3,000 to 4,000. The greatly increased air volume improves the combustion to the point where the unburned products remaining in the heated air can be tolerated to a greater extent than is the case with prior large space heaters, such that the inlets to the fans need not be located outside the building being heated.

The heater of this invention can be made with an overall width as small as thirty inches while delivering 1,000,000 B.T.U. per minute of clean air. It can thus be wheeled through the average apartment house doorway to provide auxiliary heat while the apartment house is under construction or undergoing remodeling. No ducting to exterior air is necessary. A thermostatic control (not shown) may be provided at the outlet of the heater to maintain an even temperature in the output air.

One of the advantages of the double'centriiugal fan construction is that a more uniform flow of air is obtained throughout the cross section of the plenum chamber and hence all parts of the burner are supplied with substantially equal amounts of air. In a typical single centrifugal fan, as shown in FIG. 4, there is a tendency for the air to crowd to the outside upper corner 34 of the outlet end as it leaves the fan and to produce a drop in volume vertically and horizontally across said end away from said corner. By using two centrifugal fans, one above the other and discharging into a common rectangular duct, the low volume side of the upper fan is near the high volume side of the lower fan, and the two air streams then blend together to produce a more uniform stream. Since the stream is more uniform, the combustion of the fuel is more uniform and complete.

We claim:

1. A portable space heater for providing large quantities of heated air, said heater comprising a frame, a pair of substantially identical centrifugal fans mounted on one end of said frame and disposed with their outlet ends one above and axially forward of the other, a common substantially rectangular duct of a cross sectional size and shape substantially equal to the combined cross sectional size and shape of the outlets of said fans, the outlet of the forward one of said fans being connected to the inlet of said duct, a rectangular extension connecting the outlet of the other fan to the inlet of said duct, :1 fuel burner mounted in said duct, and a plenum chamber adjacent the burner and extending horizontally to the other end of the frame.

2. A portable space heater as described in claim 1, each of said fans having inlet openings disposed transversely of the plenum chamber, and a unitary circular guard extending across the inlet openings of both fans.

3. A portable space heater as described in claim 1, said burner being rectangular in outline and extending across the outlets of both fans such that a substantially even distribution of air is effected across the burner. 

1. A portable space heater for providing large quantities of heated air, said heater comprising a frame, a pair of substantially identical centrifugal fans mounted on one end of said frame and disposed with their outlet ends one above and axially forward of the other, a common substantially rectangular duct of a cross sectional size and shape substantially equal to the combined cross sectional size and shape of the outlets of said fans, the outlet of the forward one of said fans being connected to the inlet of said duct, a rectangular extension connecting the outlet of the other fan to the inlet of said duct, a fuel burner mounted in said duct, and a plenum chamber adjacent the burner and extending horizontally to the other end of the frame.
 2. A portable space heater as described in claim 1, each of said fans having inlet openings disposed transversely of the plenum chamber, and a unitary circular guard extending across the inlet openings of both fans.
 3. A portable space heater as described in claim 1, said burner being rectangular in outline and extending across the outlets of both fans such that a substantially even distribution of air is effected across the burner. 